It is often desirable to monitor industrial fluids, such as a refinery fluid, a production fluid, refinery feedstock, combinations thereof, and/or derivatives thereof, but it has been particularly troublesome to monitor industrial fluids in a timely manner. Typically, a sample of the industrial fluid is collected at the site of the industrial fluid, but the sample is then sent to a remote location for analyzing any compositions therein. Such analytical techniques include, but are not limited to separation techniques, detection techniques, and the like. Once the results are received, the parameters related to the industrial fluid may be altered accordingly. Examples of such parameters include temperature, pH, velocity, and the like. Conditions affecting the fluid may also include the amount of fuel additives therein, such as hydrogen sulfide scavengers or other types of contaminant removal technology, neutralizers, demulsifiers, and the like.
There are many different types of detection techniques for detecting compositions within a fluid, such as surface enhanced Raman spectroscopy (SERS) (often called surface enhanced Raman scattering), which is a surface-sensitive detection technique that may be used to detect compositions adsorbed on rough metal surfaces or nanostructured surfaces.
Mass spectrometry (MS) displaying the spectra of the mass(es) for at least one molecule within a sample of material. It determines the elemental composition of a sample, the masses of compounds and of molecules, and it may elucidate the chemical structures of molecules. Mass spectrometry works by ionizing chemical compounds to generate charged molecules or molecule fragments and measuring their mass-to-charge ratios. In a typical MS procedure, a sample is ionized and the ions separate according to their mass-to-charge ratio. The signal generated from the detected ions forms a spectra where the spectra indicates the mass(es) of each compound or molecule based on known masses for a given spectra.
Nuclear magnetic resonance (NMR) spectroscopy determines the physical and chemical properties of atoms or the molecules in which they are contained by exploiting the magnetic properties of certain atomic nuclei. The analyte absorbs electromagnetic radiation at a frequency that is characteristic of the isotope. The resonant frequency, energy of the absorption, and the intensity of the signal are proportional to the strength of the magnetic field. The generated spectrum provides detailed information about the structure, dynamics, reaction state, and chemical environment of molecules.
Ultraviolet visible spectroscopy or ultraviolet visible spectrophotometry utilizes absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. This technique uses wavelengths of light in the visible and adjacent (near-UV and near-infrared (NIR)) ranges. Typically, the eluent includes an ion-pair reversed-phase system with a UV-absorbing ion, since absorption measures transitions from the ground state to the excited state. The UV spectroscopy or spectrophotometry detects or identifies the composition that absorbs UV light.
Indirect UV spectrometry allows non-ionic substances with low or no UV-absorptive properties to be detected and quantified. The mobile phase may have an uncharged component with high UV-absorbance. Polar or non-polar bonded stationary phases may be used, depending on the hydrophobic character of the analytes. Indirect UV detection may be used in applications where the composition within the sample may be or include, but not limited to organic solvents, carbohydrates, polyols, halide ions, amines, and the like.
Capacitively-coupled contactless conductivity detection (C4D) systems apply a high voltage AC waveform to a transmitter electrode adjacent to a tube or channel in which electrophoretic, electroosmotic, or chromatographic flow is occurring. As analyte ions pass into the detection region, they cause small changes to the overall sample conductivity. Continuous monitoring of the conductivity signal will show a series of peaks, the areas (or heights) of which are related to analyte concentration. The signal is processed like a conventional chromatogram. The C4D electrodes do not make direct contact with the sample. Thus, they are electrically isolated from the sample (ideal for electrophoresis detection), and electrode fouling is eliminated. Most analytes for a C4D system are ionic. Sensitivity is typically similar to UV-visible absorption detection.
Laser-induced fluorescence or LED induced fluorescence is another spectroscopic method. The composition may be examined by exciting the composition with a laser. The wavelength of the laser is one at which the composition has the largest cross-section. The composition will become excited and then de-excite (or relax) and emit light at a wavelength longer than the excitation wavelength.
‘Detection’ is defined herein as a method of confirming the presence of a composition or analyte in a fluid; whereas, ‘quantitation’ is defined herein as a method of determining the concentration of an analyte in a fluid. While detection techniques may be combined with quantitation techniques in a particular device, each technique may also be performed separately.
There are also many types of separation techniques, which include gas chromatography, ion-exchange chromatography, high performance liquid chromatography, electrokinetic chromatography (EKC), capillary isotachophoresis (CITP), capillary isoelectric focusing (CIEF), and electrophoresis, such as affinity capillary electrophoresis (ACE), non-aqueous capillary electrophoresis (NACE). Chromatography typically involves a mobile phase, a stationary phase, and an analyte; although, CEC utilizes a pseudostationary phase instead of a mobile phase.
The solution having the composition of interest is usually called a sample, and the individually separated components are called analytes. The analyte used for chromatographic purposes may have at least one composition of interest that is dissolved in a fluid, which is the mobile phase. The mobile phase carries the analyte through a structure that has a stationary phase therein. The various compositions of the analyte travel at different speeds, and the compositions separate based on differential partitioning between the mobile phase and the stationary phase. Subtle differences in a compound's partition coefficient change the rate of retention based on the type of stationary phase.
In traditional electrophoresis, electrically charged analytes move in a conductive liquid medium under the influence of an electric field. The species of compositions within a sample may be separated based on their size to charge ratio in the interior of a small capillary filled with an electrolyte. Conducting these separations in small fused silica capillaries or microchannels (10-100 μm internal diameter) allows for high voltages (up to 30 kV) to be applied, extremely small sample volume (0.1-10 μL) for the analyte, rapid separation times (minutes), and/or high resolving power (hundreds of thousands of theoretical plates). Electrophoresis may be combined with chromatographic techniques based on the type of analysis desired.
Gas chromatography (GC) separates and analyzes compounds that may be vaporized without decomposition. The mobile phase is a carrier gas, such as an inert or unreactive gas. The stationary phase may be a microscopic layer of liquid or polymer on an inert solid support inside a column, such as a piece of glass or metal tubing. Ion chromatography (or ion-exchange chromatography) separates ions and polar molecules within an analyte based on the charge of the molecules.
High-performance liquid chromatography (sometimes referred to as high-pressure liquid chromatography), HPLC, separates analytes by passing them, under high pressure, through a column filled with a stationary phase. The interactions between the analytes and the stationary phase and mobile phase lead to the separation of the analytes.
Capillary electrophoresis (CE), also known as capillary zone electrophoresis (CZE), can be used to separate ionic species by their charge and frictional forces and hydrodynamic radius similar to the generic electrophoresis technique discussed above. CE is simple to use, operates at a high speed, and requires small amounts of sample or reagents.
Gradient elution moving boundary electrophoresis (GEMBE) allows for electrophoretic separations in short (1-3 cm) capillaries or microchannels. With GEMBE, the electrophoretic migration of analytes is opposed by a bulk counterflow of separation buffer through a separation channel. The counterflow velocity varies over the course of a separation so that analytes with different electrophoretic mobilities enter the separation channel at different times and are detected as ‘moving boundary’, stepwise increases, in the detector response. The resolution of a GEMBE separation may be dependent on the rate at which the counterflow velocity is varied (rather than the length of the separation channel), and relatively high-resolution separations may be performed with short microfluidic channels or capillaries.
Capillary electrochromatography (CEC) utilizes electro osmosis to drive the mobile phase through the chromatographic bed. CEC combines two analytical techniques, i.e. HPLC and CE. In CEC, capillaries packed with an HPLC stationary phase, are subjected to a high voltage. Separation is achieved by electrophoretic migration of solutes and differential partitioning.
These types of separations and detection techniques have not been useful for detecting compositions within industrial fluids at the site of at least one industrial fluid. More so, the process of sending a sample to a remote location for performing a separation technique and/or detecting a composition often takes several days or weeks. Thus, it would be desirable to develop a method for detecting compositions within the industrial fluid at the site of the industrial fluid in a relatively short amount of time, e.g. five hours or less.